Electrical tuning of waveguide filters for radio communication is a well known technology. The usual way to implement electrical tuning devices in a waveguide is to vary the capacitive and inductive coupling in the waveguide and also to design additional structures in the waveguide to concentrate the electric field to the position where the tuning device is placed.
However, tuning of waveguide filters and other waveguide structures using pin diodes, ferroelectrics and MEMS in this way will affect the general electrical performance of the waveguide filter in a negative way. One of the absolute major problems is the resulting low effective Q-factor when for example using pin diodes or ferroelectric structures in a waveguide filter, which in turn results in high losses. MEMS-structures have also been used for tuning such filters, with the same poor result as for pin diodes and ferroelectric structures.
There is thus a need for an enhanced waveguide tuning device that is electrically controllable and an enhanced electrically tunable waveguide structure.